EDM Processing

When a strong pulse voltage is applied between the tool electrode and the workpiece (to reach the medium in the gap), it will break down where the dielectric strength is the lowest. Because the discharge area is very small and the discharge time is extremely short, the energy is highly concentrated, making the temperature of the discharge area instantaneously as high as 10000-12000 ℃, and the metal on the surface of the workpiece and the tool electrode is partially melted or even vaporized. The partially melted and vaporized metal is thrown into the working fluid under the action of explosive force, cooled into small metal particles, and then quickly washed away from the working area by the working fluid so that a tiny pit is formed on the surface of the workpiece.

After one discharge, the dielectric strength of the medium is restored and waits for the next discharge. Repeatedly so that the surface of the workpiece is continuously eroded, and the shape of the tool electrode is copied on the workpiece, to achieve the purpose of forming and processing.

Types of EDM Processing:

There are three types: Sinker EDM, wire EDM, and fast hole drilling EDM.

Sinker EDM

Sinker EDM can be called ram EDM, volume EDM, or cavity-type EDM. There are two parts: one is an electrode, and the other is a workpiece. The two parts are connected to a power supply. The workpiece is sunk in oil or dielectric fluids. When the electrode is near the workpiece, an electric spark will occur. The spark strikes each time to remove some particles away. And the shape of the electrode forms the shape of the workpiece.

Sinker EDM is used to make complex-shaped cavities.

The common applications include:

• Rapid Tooling
• Mold making
• Injection molding molds
• Dies
• Fine details
• Sharp inside corners
• Deep and thin ribs
• Blind cavities
• Blind keyways
• Internal splines
• Threads

Wire EDM

Wire EDM, also called wire-cut EDM or wire cutting or wire erosion. The electrode becomes a thin metal wire, and the diameter is around 0.05mm to 0.35mm. It is fed through the workpiece and submerged in a tank of dielectric fluid.

Wire EDM is often seen in traditional machining processes. Such as cutting very thick plates of hard metal.

The common applications include:

Thick plates

Extrusion dies

Blanking punches

Automotive and aerospace parts

Tight-tolerance parts

Medical and dental devices

Parts where burrs are unacceptable

Thin parts that could break during conventional machining

Graphite electrodes for sinker EDM

Fast hole drilling EDM

Courtesy of Beaumont Fast Hole EDM Drill

EDM hole drilling uses an energized rotating tube electrode with high-pressure flushing to produce fast and accurate machining of small deep holes in conductive metals.

This EDM method can offer the highest accuracy, reliability, and productivity and unique solutions for high-volume production applications.

EDM metal electrodes can be made from tungsten copper plates, tungsten copper rods, tungsten copper squares, and tungsten copper cubes. We offer various sizes for metallic EDM WCu materials. Grade can be chosen from 70WCu, 75WCu, to 80WCu.